A used concrete pumping truck can be purchased for $125,000. The operation costs are expected to be $65,000 the first year and increase 5% each year…

The question asks to identify the type of cost that is independent of the system's level of activity or output. By definition, fixed costs are expenses that do not change in total within a relevant range of operations, regardless of the volume of production or activity. They are incurred even if the system (e.g., the concrete truck) is idle. Examples include insurance, administrative salaries, and straight-line depreciation as mentioned in the scenario. In contrast, variable costs fluctuate in direct proportion to the system's activity. The extensive financial data provided in the question is extraneous information designed to test the candidate's ability to identify the core definitional concept being asked.

A. no answers are correct: This is incorrect because "fixed costs" is the precise economic term for costs that are independent of the system's activity level.
B. both fixed and variable costs: This is incorrect because variable costs are, by definition, dependent on and vary with the system's level of activity.
C. variable costs fixed costs: Assuming this means "variable costs," it is incorrect as these costs are directly influenced by changes in the system's output.

1. AACE International, Skills & Knowledge of Cost Engineering, 6th Ed., (Morgantown, WV: AACE International, 2015), Section 1.3.2, "Cost Classifications."

This section defines a Fixed Cost as: "Costs that are unaffected by changes in activity level over a feasible range of operations for the capacity or capability available." It defines a Variable Cost as: "Costs that are influenced by changes in activity level." This directly supports that only fixed costs are independent of the system.

2. Hollmann, J. K., Editor, Total Cost Management Framework: An Integrated Approach to Portfolio, Program, and Project Management, 2nd Ed., (Morgantown, WV: AACE International, 2015), Section 7.1.1, "Cost Estimating and Budgeting Concepts."

This foundational AACE text explains cost behavior, stating that fixed costs "remain constant in total regardless of changes in the volume of activity," while variable costs "vary in total with the volume of activity." This reinforces the correct answer.

3. Sullivan, W. G., Wicks, E. M., & Koelling, C. P., Engineering Economy, 17th Ed., (Pearson, 2018), Chapter 2, Section 2.2.1, "Fixed, Variable, and Incremental Costs."

This standard university textbook on engineering economics defines fixed costs as those "unaffected by changes in activity level over a feasible range of operations." This academic source confirms the fundamental principle tested in the question.